我们最近报道了α7和α3β4烟碱乙酰胆碱受体(nAChR)亚型在人嗜铬细胞的质膜中表达,在那里它们共定位并物理相互作用。本研究旨在评估这些受体亚型是否也在中枢神经系统共同定位以相互作用,以及它们的表达和共定位是否受磷酸化/去磷酸化过程的调节,就像它们在人类嗜铬细胞中一样。我们在这里发现,在分离和维持培养的小鼠海马神经元中,酪氨酸(Tyr)-和丝氨酸/苏氨酸(Ser/Thr)-磷酸酶抑制降低了nAChR表达和α7,而不是α3β4,nAChR亚型的共定位。然而,Tyr激酶抑制或蛋白磷酸酶2A(PP2A)激活增加了α3β4nAChR的表达,减少受体亚型共定位。此外,如果Tyr-磷酸酶和激酶的抑制剂,或Ser/Thr-磷酸酶的抑制剂和PP2A的激活剂一起施用。因此,Tyr-和Ser/Thr激酶和磷酸酶对α7和α3β4nAChR亚型表达的调节在小鼠海马神经元中表现出不同的机制。nAChR亚型的共定位,然而,任何影响这些激酶或磷酸酶的动作都会改变,这可能对nAChR亚型的功能活性产生影响。
We have recently reported that α7 and α3β4 nicotinic acetylcholine receptor (nAChR) subtypes are expressed in human chromaffin cells in the plasma membrane where they colocalize and physically interact. The present study was designed to evaluate whether those receptor subtypes also colocalize at the central nervous system to mutually interact, and whether their expression and colocalization are regulated by phosphorylation/dephosphorylation processes, as they are in human chromaffin cells. We have here found that in isolated and maintained in culture mouse hippocampal neurons, nAChR expression and colocalization of α7, but not α3β4, nAChR subtypes decreased by tyrosine (Tyr)- and serine/threonine (Ser/Thr)-phosphatase inhibition. However, Tyr-kinase inhibition or protein-phosphatase 2A (PP2A) activation increased α3β4 nAChR expression, diminishing receptor subtypes colocalization. Furthermore, colocalization is not recovered if the inhibitors of Tyr-phosphatase and kinases, or the inhibitor of Ser/Thr-phosphatases and the activator of PP2A are applied together. Therefore, regulation of α7 and α3β4 nAChR subtypes expression by Tyr- and Ser/Thr kinases and phosphatases exhibit differential mechanisms in mouse hippocampal neurons. Colocalization of nAChR subtypes, however, is altered by any maneuver that affects these kinases or phosphatases, which might have consequences in the functional activity of nAChR subtypes.